1. Field of the Invention
The present invention relates to an optical box as a plastic molding which can be mounted in and removed from an image forming apparatus. The optical box holds optical parts in it. The invention also relates to an optical scanner including such an optical box. The invention further relates to an image forming apparatus including such a scanner.
2. Description of the Related Art
An optical box as a plastic molding for an optical scanner or the like needs to be sufficiently dust-proof because the box holds optical parts in it. Conventionally, optical boxes, each of which includes an optical housing and a lid, have been so devised in various forms as to prevent dust from entering the box through the gaps between the housing and the lid.
The prior art includes JP-2000-258712-A, which discloses an optical scanner including an optical box. This optical box includes an optical housing and a lid as a plastic molding shaped for the open side of the housing. The lid is screwed firmly to the housing so as to prevent dust from entering the optical box. When the lid is screwed to the housing, resin swarfs are produced, which may unfavorably affect the functions of the collimator lenses and other optical parts of the scanner.
Attempts have been made to engage a lid with an optical housing without using screws. However, it has been difficult to design a sufficiently dust-proof optical box as a plastic molding which is easy to make.
In recent years, for unit maintenance and unit disposal, it has been important to guarantee easy mounting of an optical box in an image forming apparatus and easy removal of the box from the apparatus.
One object of the present invention is to provide a dust-proof optical box which is easy to manufacture, mount in an image forming apparatus, and remove from the apparatus. Another object is to provide an optical scanner including such an optical box. Still another object is to provide an image forming apparatus including such a scanner.